Change ATF in a 2006 Cadillac DTS at 28,000 miles?

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I picked up a 2006 Cadillac DTS with 28,000 miles. I was wondering if I should change the ATF as it is 12 years old. If so, should I take it to the Cadillac dealer and have it flushed and refilled or should I drop the pan? Also, what is the best Dexron VI to use? I'm open to all suggestions. Thanks!
 
You can drop the pan, however the 4T80 transmission is one of GM's BEST EVER. I highly doubt it needs doing.

If you do it yourself, here's a couple tips:

The "filters" under the bottom pan are no more than screens. They do NOT need to be replaced, just flush them out with carb clean or brake clean or hot water or whatever and dry them.

This is a "dry sump" transmission. The fluid in the bottom is barely 1/8th the total capacity. There is an ADDITIONAL drain plug inside, accessible once the lower pan is off. Once you remove the pan, there's a 7/16 (11mm) plug that must be removed to completely drain the trans.

It will take more than the average trans service to refill, somewhere around 8 quarts IIRC.

Like I said originally, these transmissions are almost bulletproof. The early ones had shift solenoid issues, but that was rectified in mid-00 I believe. I've had one of these bad boys apart, the parts inside are MASSIVE. Even the N* is no real challenge for the 4T80. If GM had been able to squeeze a 4T80 behind the 5.3 in the Impala SS/Grand Prix GXP/Buick Lacrosse super, they would have had a lot fewer issues. Unfortunately, the '80 is a huge trans and just won't fit...
 
I'd change it if the fluid is not bright reddish/pink and essentially clear. Even if the trans is nearly bullet-proof...fluid certainly isn't. You also can't be sure what fluid is currently in the transmission...though you can "assume" it's a 100% factory fill. From what I've read some do these as early as 25K miles, others at 35-50K miles, and others go all the way to the factory fill 100K miles/3-5 years limit. About half the fluid drains by gravity. You'd have to do a cooler line exchange to get it all out....or do several feed and bleeds. A service now will get any clutch wear-in materials out of the system.
 
If its like my wife's 06 STS, 4.6L It does not have a dip stick, check for a filler tube before you drain it. Prolly don't have one. I took my wife's to my friends transmission shop and had him do it, you need a pump to pump the fluid into a plug filler hole on the side of the trans. They made it unfriendly! No flush any more, drain and fill, that's if you even decide to do so. And Dex6. I just bought it at the dealer.

You can make a pump set up from a gear oil pump and a clear hose/tube. Measure the amount of fluid added back in to match what you drained, and also check how much fluid capacity for a trans fluid service. They should all match up.
 
Originally Posted By: KneeGrinder
If its like my wife's 06 STS, 4.6L It does not have a dip stick, check for a filler tube before you drain it. Prolly don't have one. I took my wife's to my friends transmission shop and had him do it, you need a pump to pump the fluid into a plug filler hole on the side of the trans. They made it unfriendly! No flush any more, drain and fill, that's if you even decide to do so. And Dex6. I just bought it at the dealer.

You can make a pump set up from a gear oil pump and a clear hose/tube. Measure the amount of fluid added back in to match what you drained, and also check how much fluid capacity for a trans fluid service. They should all match up.


Totally different car and trans. The DTS has a dipstick built in to the cap of the fill hole. Easy as pie.
 
Unfortunately, Dorman does not make a transmission pan for the 4T80, so the next best thing would be to get a new OEM pan and the B&M drain plug kit and add a drain plug that way. This will make future ATF changes much easier
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Use Maxlife ATF, or Castrol Full Synthetic ATF.
 
Thanks for the advice. I think I will drop the pan and clean up the screens this summer and do a cooler line fluid exchange to get the rest.
 
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